Multi-stage Fracturing Sliding Sleeve

ABSTRACT

The present invention provides a multi-stage fracturing sliding sleeve, with a fracturing ring, a ball seat bearing, a first sliding ring and a limiting ring arranged from top to bottom along a fracturing pipe. All of the fracturing ring, the ball seat bearing and the first sliding ring are in sliding connection with the fracturing pipe, and the fracturing ring forms plugging by sealing fracturing holes in the fracturing pipe in a natural state; the ball seat bearing and the fracturing pipe are connected through first shear pins; a first spring is arranged between the first sliding ring and the limiting ring; the limiting ring limits the axial position of the first sliding ring; multi-blade ball seats are arranged in the ball seat bearing. With a two-stage shear structure, the structure is simplified, and multi-stage fracturing construction can be realized without reducing the inner diameter.

This application claims priority to Chinese Patent Application No. 201810618056.1 filed on Jun. 15, 2018, the disclosure of which is hereby incorporated in its entirety by reference.

FIELD

The present invention relates to the field of underground construction equipment in the process of secondary development of old wells in oil gas fields and non-conventional energy development, especially a multi-stage fracturing sliding sleeve.

BACKGROUND

In order to further exploit the production capacity of producing wells in oil gas fields, improve the production efficiency of shale gas producing wells or geothermal development wells and maintain the yield, parts of the wells need to be, for example, fractured within the production cycle of the producing wells. Since producing formations are buried in strata ranging from hundreds to thousands of meters in depth and divided into a plurality of bed series, there are inevitable differences among the formations influenced by various factors. To maximize the potential of each formation, each single formation needs to be treated as far as possible. The previous staging method is mainly of a ball seat bearing type, namely that the inner diameter of the bail seat bearing becomes smaller and smaller from top to bottom. This seriously restricts the increase of the stage number of acid fracturing and the improvement of scale.

The technical solution of the prior art is that: in terms of the segmented stage number of staged fracturing abroad, 0.125 in (3.175 mm) is generally the first stage, with the minimum inner diameter of 1.25 in (31.75 mm). If oil pipes with the specification of 2 ⅞ in×5.5 mm are used, the maximum arrangement can only be 52.5 mm (the ball is 0.25 in (i.e., 6.35 mm) larger than the ball seat bearing), that is to say, only 6.5 stages can he arranged within the oil pipes with the specification of 2 ⅞ in×5.5 mm, and the maximum arrangement is 7 stages.

An unlimited-stage sliding sleeve and a technological method are recorded in the Chinese patent document CN 105089601 A, which solve the technical problem, by a sealing displacement mechanism of split claws, and thee inner diameters of flow passages are kept in consistency, but not at the expense of the inner diameters. Multi-stage fracturing can be realized in theory. But the structure is relatively complex, and the use reliability is difficult to guarantee.

Further, the demand for geothermal or underground temperature regulation of high temperature oil and gas reservoirs and dry hot rocks in the prior art also puts forward higher requirements for fracturing construction, for example, we hope to achieve fracturing construction for many times in one fracturing section, but there is no relatively mature solution in the prior art. For another example, higher fracturing pressure is needed in the prior art, if 60 MPa is to be reached, clearances which are difficult to seal exist between the pitching ball and the ball seat bearing, such as clearances between the split claws along the circumference, and these clearances make it more difficult to increase the pressure. Therefore, a fracturing sliding sleeve capable of precisely controlling and realizing opening for many times provided that the inner pipe bore diameter is guaranteed needs to be designed to ensure that the fracturing process is carried out

SUMMARY

The technical problem to be solved in the invention is to provide a multi-stage fracturing sliding sleeve which can realize multi-stage sleeve connection, the structure is compact and concise, and the sliding sleeve is convenient to operate. In a preferred solution, fracturing construction for many times can be realized in one fracturing section, and the pressure for fracturing construction can be improved.

In order to solve the above technical problem, the technical solution used in the invention is: a multi-stage fracturing sliding sleeve, which comprises joint members, a fracturing pipe and a two-stage shear gliding device.

A fracturing ring, a ball seat bearing, a first sliding ring and a limiting ring are arranged from top to bottom along a fracturing pipe, forming a one-stage shear gliding device; all of the fracturing ring, the ball seat bearing and the first sliding ring are in sliding connection with the fracturing pipe, wherein the fracturing ring forms plugging by sealing fracturing holes in the fracturing pipe in a natural state; the ball seat bearing and the fracturing pipe are connected through at least one first shear pin; a first spring is arranged between the first sliding ring and the limiting ring; the limiting ring limits the axial position of the first sliding ring.

A plurality of slidable multi-blade ball seats are arranged in the ball seat bearing which is fit to the slidable multi-blade ball seats through an inclined plane, when the multi-blade ball seats slide down, the diameter passing through the section between the multi-blade ball seats increases.

A second sliding ring is arranged below the multi-blade ball seats and connected with the first sliding ring in a sliding mode; the second sliding ring and the first sliding ring are connected through the second shear pins.

In the preferred solution, the total shear force of the second shear pins is greater than that of the first shear pin.

In the preferred solution, a third spring is arranged between the second shear pins and the second sliding ring so that the second shear pins tend to pop out to be connected with the first sliding ring.

In the preferred solution, a plurality of second shear pin holes connected with the second shear pins are formed in the first sliding ring and divided into a plurality of groups which are distributed in a staggered mode in the axial direction of the first sliding ring.

A second spring is arranged between the second sliding ring and the first sliding ring.

In the preferred solution, the staggering distance between several groups of second shear pin holes is smaller than the travel for the fracturing ring to open the fracturing holes in a sliding mode.

In the preferred solution, the fracturing ring is connected with the ball seat bearing, and a first seal ring is arranged between the fracturing ring and the fracturing pipe at the upstream of the fracturing holes.

In the preferred solution, a cylindrical seat is arranged at an upper end face of the ball seat bearing, and the cylindrical seat and the outer wall of the pitching ball form a seal structure.

In the preferred solution, the pitching ball is a sphere or a block with reducing curved surfaces at both ends and a cylindrical section in the middle.

In the preferred solution, a one-stage bench is arranged at the outer wall of the first sliding ring, a one-stage bench is arranged at the inner wall of the limiting ring, the first spring is located between the two benches, and the upper end face of the limiting ring and the bench of the first sliding ring form an axial limiting structure.

In the preferred solution, an expanded annular structure is formed at the top of the second sliding ring, and the second shear pins are movably installed in the annular structure.

A two-stage bench is arranged at the inner wall of the first sliding ring, an, axial limiting structure is formed between an upper bench and the annular structure, and a lower bench is used to install the second spring.

The invention provides a multi-stage fracturing sliding sleeve. By using the two-stage shear structure, the structure of the fracturing sliding sleeve in the prior art is greatly simplified, and multi-stage fracturing construction can be realized without reducing the inner diameter. In the preferred solution, the provision of the second shear pin holes distributed in a staggered mode enables re-connection and re-shearing of the second shear pin holes at different heights to realize fracturing construction for many times after the second sliding ring is reset. The structure of the cylindrical seat is provided in such a way that a seal structure is directly formed between the ball seat bearing and the pitching ball, so that the sealing requirement for the clearances between the circumferences of the multi-blade ball seats is greatly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The multi-stage fracturing sliding sleeve is, further illustrated below in combination with the figures and embodiments:

FIG. 1 is a diagram of the section structure of the multi-stage fracturing sliding sleeve.

FIG. 2 is a structure diagram of the outer wall of the second sliding ring and the inner wall of the first sliding ring which are unfolded along the circumference.

FIG. 3 is a diagram of the semi-section structure of the multi-stage fracturing sliding sleeve.

FIG. 4 is a top view of the ball seat bearing and the multi-blade ball seats in the multi-stage fracturing sliding sleeve.

FIG. 5 is a main view of the multi-stage fracturing sliding sleeve.

FIG. 6 is a three-dimensional diagram of one blade of the multi-blade ball seats in the multi-stage fracturing sliding sleeve.

FIG. 7 is a three-dimensional diagram of the ball seat bearing in the multi-stage fracturing sliding sleeve.

In the figures: upper joint 1, fracturing pipe 2, first seal ring 3, cylindrical seat 4, fracturing ring 5, ball seat bearing 6, multi-blade ball seats 7, third spring 8, second shear pins 9, second sliding ring 10, second spring 11, first sliding ring 12, second seal ring 13, first spring 14, limiting ring 15, third seal ring 16, lower joint 17, pitching ball 18, fracturing holes 19, second shear pin holes 21.

DETAILED DESCRIPTION Embodiment 1

As shown in FIG. 1, a multi-stage fracturing sliding sleeve, which comprises joint members, such as the upper joint 1, the lower joint 17, the fracturing pipe 2 and the two-stage shear gliding device in FIG. 1; fracturing holes 19 distributed along the circumference are formed in the outer wall of the fracturing pipe 2.

The fracturing ring 5, ball seat bearing 6, first sliding ring 12 and limiting ring 15 are arranged from top to bottom along the fracturing pipe 2, forming the one-stage shear gliding device; all of the fracturing ring 5, the ball seat bearing 6 and the first sliding ring 12 are in sliding connection with the fracturing pipe 2; the fracturing ring 5, the ball seat bearing 6 and the first sliding ring 12 are fixedly connected. Preferably, the connection between the fracturing ring 5 and the ball seat bearing 6 is threaded or interference fit, and the connection between the ball seat bearing 6 and the first sliding ring 12 is threaded or interference fit, wherein the fracturing ring 5 forms plugging by sealing the fracturing holes 19 in the fracturing pipe 2 in a natural state; in a working state, the fracturing pipe 2 opens the fracturing holes 19 influenced by a hydraulic medium on the thrust of the pitching ball 18. The ball seat bearing 6 and the fracturing pipe 2 are connected through at least one first shear pin 20. A first spring 14 is arranged between the first sliding ring 12 and the limiting ring 15, and the limiting ring 15 limits the axial position of the first sliding ring 12.

As shown in FIGS. 1, 6 and 7, slidable multi-blade ball seats 7 are arranged in the ball seat bearing 6 which is fit to the slidable multi-blade ball seats 7 through an inclined plane. In this case, the multi-blade ball seats 7 are in a three-blade structure, and the three-blade multi-blade ball seats 7 form a circular ring as a whole. Bosses are formed at the back of the multi-blade ball seats 7, chutes are formed on the inner wall of the ball seat bearing 6, and the bosses slide in the chutes to have the effect of limiting. An inner inclined plane is formed on the inner wall of the ball, seat bearing 6, and an outer inclined plane is formed on the outer wall of each multi-blade ball seat 7. When the multi-blade ball seats 7 slide down, the multi-blade structure between the multi-blade ball seats 7 is radially unfolded, and the diameter passing through the section between the multi-blade ball seats 7 increases so that the pitching ball 18 can pass through the next stage of fracturing sliding sleeve.

The second sliding ring 10 is arranged below the multi-blade ball seats 7, the second sliding ring 10 limits the axial position of the multi-blade ball seats 7, the second sliding ring 10 is in sliding connection with the first sliding ring 12, and the second seal ring 13 is arranged between the second sliding ring 10 and the first sliding ring 12. The second sliding ring 10 and the first sliding ring 12 are connected through the second shear pins 9. In the preferred solution, the total shear force of the second shear pins 9 is greater than that of the first shear pin 20. With this structure, after descending to the well, put the pitching ball 18 into the position of the ball seat bearing 6 so that the pitching ball 18 is limited by the multi blade ball seats 7, continue to input the pressure medium, the pressure value at this time is the first pressure, for example, 5-10 MPa, the first pressure acting on the pitching ball 18 is enough to shear the first shear pin 20 off, the ball seat bearing 6 drives the fracturing ring 5 and the first sliding ring 12 to go down, the first shear pin 20 is sheared off, and the first spring 14 is compressed so that the fracturing holes 19 are opened to realize the fracturing construction of the hydrocarbon reservoir. When the fracturing construction is completed, continue to input the pressure medium, the pressure value at this time is the second pressure, for example, 15-20 MPa, the pitching ball 18 drives the multi-blade ball seats 7 to go down, and the second spring 11 is compressed. The multi-blade ball seats 7 expand the through-hole diameter in the process of going down until it is enough for the pitching ball 18 to pass through. When the pitching ball 18 passes through the multi-blade ball seats 7, the fracturing ring 5, the ball seat bearing 6, the multi-blade ball seats 7, the second sliding ring 10 and the first sliding ring 12 are reset under the action of the second spring 11 and the first spring 14, and the fracturing holes 19 on this section are re-plugged.

Embodiment 2

On the basis of embodiment 1, in the preferred solution, as in FIGS. 1 and 3, a third spring 8 is arranged between the second shear pins 9 and the second sliding ring 10 so that the second shear pins 9 tend to pop out to be connected with the first sliding ring 12. With this structure, the second shear pins 9 can be connected with the first sliding ring 12 again so it is easy to shear off again to realize secondary fracturing operation.

Embodiment 3

On the basis of embodiment 1 or 2, in the further preferred solution, as in FIG. 2, a plurality of second shear pin holes 21 connected with the second shear pins 9 are formed in the first sliding ring 12, the second shear pin holes 21 are divided into a plurality of groups which are distributed in a staggered mode in the axial direction of the first sliding ring 12, and the second spring 11 is arranged between the second sliding ring 10 and the first sliding ring 12. With this structure, the second shear pins 9 and the second shear pin holes 21 between different groups are connected with each other, thus achieving more reliable re-fracturing operation. In this case., a group of second shear pins 9 at the bottom are interconnected with the second shear pin holes 21, and a group of second shear pins 9 at upper level are connected with the second shear pin holes 21 after resetting, until the a group of second shear pins 9 at the top are connected. A combination of this case and embodiment 2 enables fracturing construction for many times, preferably 2-3 times.

In the preferred solution, as in FIGS. 1 and 2, the staggering distance between several groups of second shear pin boles 21 is smaller than the travel for the fracturing ring 5 to open the fracturing holes 19 in a sliding mode, for example, h in FIGS. 1 and 2.

Embodiment 4

On the basis of embodiments 1-3, in the preferred solution, the fracturing ring 5 is connected with the ball seat bearing 6, and the first seal ring 3 is arranged between the fracturing ring 5 and the fracturing pipe 2 at the upstream of the fracturing holes 19.

In the preferred solution, the cylindrical seat 4 is arranged at the upper end face of the ball seat bearing 6, and a seal structure is directly formed by the cylindrical seat 4 and the outer wall of the pitching ball 18. With this structure, the requirement for sealing between the multi-blade ball seats 7 is reduced, so that a pressure medium with, greater pressure can be withstood. In the alternative solution, an integrated structure is formed between the cylindrical seat 4 and the ball seat bearing 6, and processing and installation are facilitated with this structure, as shown in FIG. 1. In another alternative solution, a split structure is formed between the cylindrical seat 4 and the ball seat bearing 6, the cylindrical seat 4 and the fracturing ring 5 are fixedly connected by threaded or interference fit, and the fracturing ring 5 and the ball seat bearing 6 are fixedly connected by threaded or interference fit. With this structure, it is easy to make the cylindrical seat 4 using a softer material such as copper or copper alloy to improve the sealing effect.

In the preferred solution, the pitching ball 18 is, a sphere, as shown in FIG. 1, or a block with reducing curved surfaces at both ends and a cylindrical section in the middle, as shown in FIG. 3. With this structure, better sealing between the pitching ball 18 and the cylindrical seat 4 can be realized.

In the preferred solution, the one-stage bench is arranged at the outer wall of the first sliding ring 12, the one-stage bench is arranged at the inner wall of the limiting ring 15, the first, spring 14 is located between the two benches, and the upper end face of the limiting ring 15 and the bench of the first sliding ring 12 form the axial limiting structure.

In the preferred solution, the expanded annular structure is formed at the top of the second sliding ring 10, and the second shear pins 9 are movably installed in the annular structure.

The two-stage bench is arranged at the inner wall of the first sliding ring 12, an axial limiting structure is formed between the upper bench and the annular structure, and the lower bench is used to install the second spring 11.

After descending to the well, put the pitching ball 18 into the position of the ball seat, bearing 6 and form sealing with the cylindrical seat 4, so that the pitching ball 18 is limited by the multi-blade ball seats 7, continue to input the pressure medium, the pressure value at this time is the first pressure, for example, 5-10 MPa, the first pressure acting on the pitching ball 18 is enough to shear the first shear pin 20 off, the ball seat bearing 6 drives the fracturing ring 5 and the first sliding ring 12 to go down, the first shear pin 20 is sheared off, and the first spring 14 is compressed so that the fracturing holes 19 are opened to realize the fracturing construction of the hydrocarbon reservoir. When the fracturing construction is completed, continue to input the pressure medium, the pressure value at this time is the second pressure, for example, 15-20 MPa, the pitching ball 18 drives the multi-blade ball seats 7 to go down, and the second spring 11 is compressed. The multi-blade ball seats 7 expand the through-hole diameter in the process of going down until it is enough for the pitching ball 18 to pass through. When the pitching ball 18 passes through the multi-blade ball seats 7, the fracturing ring 5, the ball seat bearing 6, the multi-blade ball seats 7, the second sliding ring 10 and the first sliding ring 12 are reset under the action of the second spring 11 and the first spring 14, and the fracturing holes 19 on this section are re-plugged. Since the second shear pin holes 21 on the first sliding ring 12 are arranged in a staggered mode, another group of second shear pins 9 and the second shear pin holes 21 are connected with each other during resetting to wait for the next fracturing construction.

The above embodiments are only preferred technical solutions of the present invention, and they should not be construed as to limit the present invention in any way. The embodiments in this application and the features in the embodiments can be combined with each other arbitrarily without conflict. The scope of protection of the invention shall take the technical solution recorded in the claim, including the equivalent alternative solution of the technical features in the technical solution recorded in the claim, as the scope of protection. That is to say, the equivalent alternative improvement within this scope is also within the scope of protection of the invention. 

What is claimed is:
 1. A multi-stage fracturing sliding sleeve, comprising joint members, a fracturing pipe and a two-stage shear gliding device, wherein a fracturing ring, a ball seat bearing, a first sliding ring and a limiting ring are arranged from top to bottom along the fracturing pipe, forming a one-stage shear gliding device; all of the fracturing ring, the ball seat bearing and the first sliding ring are in sliding connection with the fracturing pipe, wherein the fracturing ring forms plugging by sealing fracturing holes in the fracturing pipe in a natural state; the ball seat bearing and the fracturing pipe are connected through at least one first, shear pin; a first spring is arranged between the first sliding ring and the limiting ring; the limiting ring limits an axial position of the first sliding ring; slidable multi-blade ball seats are arranged in the ball seat bearing which is fit to the slidable multi-blade ball seats through an inclined plane, when the multi-blade ball seats slide down, a diameter passing through a section between the multi-blade ball seats increases; a second sliding ring is arranged below the multi-blade ball seats and connected with the first sliding ring in a sliding mode; the second sliding ring and the first sliding ring are connected through second shear pins.
 2. The multi-stage fracturing sliding sleeve according to claim 1, wherein, a total shear force of the second shear pins is greater than that of the first shear pins.
 3. The multi-stage fracturing sliding sleeve according to claim 1, wherein, a third spring is arranged between, the second shear pins and the second sliding ring so that the second shear pins tend to pop out to be connected with the first sliding ring.
 4. The multi-stage fracturing sliding sleeve according to claim 2, wherein, a third spring is arranged between the second shear pins and the second sliding ring so that the second shear pins tend to pop out to be connected with the first sliding ring.
 5. The multi-stage fracturing sliding sleeve according to claim 4, wherein, a plurality of second shear pin holes connected with the second shear pins are formed in the first sliding ring and divided into a plurality of groups which are distributed in a staggered mode in the axial direction of the first sliding ring; a second spring is arranged between the second sliding ring and the first sliding ring.
 6. The multi-stage fracturing sliding sleeve according to claim 5, wherein, the staggering distance between several groups of second shear pin holes is smaller than the travel for the fracturing ring to open the fracturing holes in a sliding mode.
 7. The multi-stage fracturing sliding sleeve according to claim 1, wherein, the fracturing ring is connected with the ball seat bearing, and a first seal ring is arranged between the fracturing ring and the fracturing pipe at an upstream of the fracturing holes.
 8. The multi-stage fracturing sliding sleeve according to claim 1 wherein, a cylindrical seat is arranged at an upper end face of the ball seat bearing; the cylindrical seat and an outer wall of the pitching ball form a seal structure.
 9. The multi-stage fracturing sliding sleeve according to claim 2, wherein, a cylindrical seat is arranged at an upper end face of the ball seat bearing; the cylindrical seat and an outer wall of the pitching ball form a seal structure.
 10. The multi-stage fracturing sliding sleeve according to claim 3, wherein, a cylindrical seat is arranged at an upper end face of the ball seat bearing; the cylindrical seat and an outer wall of the pitching ball form a seal structure.
 11. The multi-stage fracturing sliding sleeve according to claim 4, wherein, a cylindrical seat is arranged at an upper end face of the ball seat bearing; the cylindrical seat and an outer wall of the pitching ball form a seal structure,
 12. The multi-stage fracturing sliding sleeve according to claim 5, wherein, a cylindrical seat is arranged at an upper end face of the ball seat bearing; the cylindrical seat and an outer wall of the pitching ball form a seal structure.
 13. The multi-stage fracturing sliding sleeve according to claim 6, wherein, a cylindrical seat is arranged at an upper end face of the ball seat bearing; the cylindrical seat and an outer wall of the pitching ball form a seal structure.
 14. The multi-stage fracturing sliding sleeve according to claim 7, wherein, a cylindrical seat is arranged at an upper end face of the ball seat bearing; the cylindrical seat and an outer wall of the pitching ball form a seal structure.
 15. The multi-stage fracturing sliding sleeve according to claim 11, wherein, the pitching ball is a sphere or a block with reducing curved surfaces at both ends and a cylindrical section in the middle.
 16. The multi-stage fracturing sliding sleeve according to claim 12, wherein, the pitching ball is a sphere or a block with reducing curved surfaces at both ends and a cylindrical section in the middle.
 17. The multi-stage fracturing sliding sleeve according to claim 13, wherein, the pitching ball is a sphere or a block with reducing curved surfaces at both ends and a cylindrical section in the middle.
 18. The multi-stage fracturing sliding sleeve according to claim 14, wherein, the pitching ball is a sphere or a block with reducing curved surfaces at both ends and a cylindrical section in the middle.
 19. The multi-stage fracturing sliding sleeve according to claim 1, wherein, a one-stage bench is arranged at an outer wall of the first sliding ring, a one-stage bench is arranged at an inner wall of the limiting ring, the first spring is located between the two benches, and an upper end face of the limiting ring and the bench of the first sliding ring form an axial limiting structure.
 20. The multi-stage fracturing sliding sleeve according to claim 1, wherein, an expanded annular structure is formed at the top of the second sliding ring, and the second shear pins are movably installed in the annular structure; a two-stage bench is arranged at an inner wall of the first sliding ring, an axial limiting structure is formed between an upper bench and the annular structure, and a lower bench is used to install the second spring. 